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F. P. PRINDLE. METHOD OF MAKING CORRUGATED FASTENERS. APPLICATION HLED MAR.8, l9l8- RENEWED FEB. I. ma.

Patented Nov; 11, 1919.

l/VVE/VTOR FM f? BY 7 AUURNEKY UNITED STATES PATENT OFFICE.

FRANK r. PRINDLR', or New BRITAIN, CONNECTICUT, AssIeNoR To THE STANLEY woRKs, on NEW BRITAIN, CONNECTICUT, A CoRroRATIoN or CONNECTICUT.

METHOD OF MAKING CORRUGATED FASTFJN Specification of Letters Patent.

Patented Nov. 11, 1919.

Original application filed March 30, 1916, Serial No. 87,710. Divided and this application filed March 8, 1918, Serial No. 221,128. Renewed February 1, 1919. Serial No. 274,588.

To all whom it may concern:

Be it known that I, FRANK P. PRINDLE, of New Britain, in the county of Hartford, and in the State of Connecticut, have invented a certain new and useful Improvement in Methods of Making Corrugated Fasteners, and do hereby declare that the following is a full, clear, and exact description thereof.

The object of my invention has been to provide a method of making corrugated fasteners which shall be more efficient in op eration than, and as cheap as, any other corrugated fastener known to me, and to such ends my invention consists in the method of making corrugated fasteners hereinafter specified. This application is a division of my prioigapplication, Serial No. 87,710 filed March 80, 1916, entitled Corrugated fastener.

in the accompanying drawings Figure 1 is a perspective view of a fastener embodying my invention;

Fig. 2 is a top plan of such a fastener (drawn on an nlarged scale) Fig. 3 is a transverse sectional view taken on the line X X of Fig. 2, and looking in the direction of the arrows; and

Fig. 4 is a crosssectional view showing the beveled edge of the fastener.

My invention is capable of practice by the use of different steps or operations, and while T have chosen the best embodiment thereof known to me, such embodiment is to be regarded as typical only, and my invention is not to be confined thereto except as required by the scope of the appended claims.

Prior to my invention, previous corrugated fasteners, as far as known to me, have had one or more of the following disadvantages:

Where there have been straight or chisel points on the entering edge, they have been formed by the meeting of a single beveled surface with a vertical surface, and have thus not cut to the best advantage, making the fastener difficult to drive and liable to break the grain instead of making a clean cut.

Where chisel points have been provided, the notches or reentrant portions between them have been sharp only along a portion of their edges.

Such re'ntrant portions have also been sharpened only by a single beveled surface meeting a perpendicular surfacea construction which is both hard to drive and tends to tear the wood to some extent.

l/Vhere cutting points have been provided, they have been of such excessive length as to narrow and therefore weaken the body of the fastener.

Such fasteners have either used a sinuous, curved shape in horizontal cross-section, with curved corrugations, aconstruction in which a large part of the cutting edge cuts across the grain of the wood when used to join the edges of boards, as is frequently done, and therefore tends to break the grain, or a V-shape corrugation in horizontal crosssection was used, in which the cutting edge all had one level, which could take no adequate advantage of the Vshape corrugations.

Where cutting points having notches between them have been used in the prior art, the cutting edges formed in these reentrant portions have been curved, a construction which does not enter the wood to the best advantage, nor always make a thoroughly clean cut.

The making of such previous fasteners has required an excessive length of blank strips, and th cutting away of an undesirably large amount of material to form the cutting edges and throats.

The making of the rounded corrugations has also caused the forming rolls to constantly wear out of shape.

The making of the rolls for forming the rounded corrugations is diflicult on account of the necessity of having specially shaped cutters which must be accurately ground.

It has been th object of my invention to overcome these objections, and they are eliminated more or less completely by the embodiment of my invention by which I shall illustrate it.

According to the method of making the fastener which I prefer I take the strip of metal. of which the fastener is to be made. and while it is yet straight, before being corrugated, I bevel the edge which is to form the entering edge of the fastener. The edge is preferably beveled 011 both sides of its median line. This beveling being done while the strip is flat maybe done by shaving with stationary or oscillating knives, by

'- of the flat portions 3, this operation both to penetrate most effectively.

forming and sharpening the notches between the'chisel points 4. Thelength of the chisel points is determined by the depth of the cut forming the notches and the chisel points can be reduced to mere edges in the longitudinal axis of the fastener, by causing such cuts, upon opposite sides, to median hne.

A fastener made according to the above meet at the method, has thefollowing advantages:

The entire entering edge of the fastener is a cutting edge; that is,,not only do the points 4 have chisel shaped edges throughout their length, but the edges of the notches are beveled from point to point and form cutting edges.

The chisel points being formed by a double bevel (that is by an inclined surface on each side of the cutting edge), enter the wood much more easily than do the chisel points which are formed by the meeting of a single beveled surface with a vertical surface. Moreover, with a given size of corrugation', the chisel points tend less to tear the wood because they are more nearly in line with the direction of the grain, than is the case when rounded corrugations areused, which enables them to penetrate between the fibers of the wood instead of having to cut across the grain.

The edges of the notches being substantially straight lines and meeting at a point at the bottom of the notch, cut to much better advantage, because the cutting edge is sharply inclined to the horizontal and nowhere is horizontal.

The cutting edges 8 of the notch are formed by the meeting of two beveled surfaces, namely, the original bevel on the inside of the corrugation and the bevel 9 on the outside thereof, and thus they are able Moreover, as the cutting edges 8 are inclined pretty nearly in the general direction of the grain, as well as inclined to the vertical, the danger of tearing the wood and breaking the grain is reduced .to a minimum as is also the force required to drive them into the wood. The removal of the metal to form the notches having been facilitated by the previous beveling of theedge of the strip, the thickness of the chip removed to finally form the notches is less than it would otherwise be.

Although the notches are sharp throughout, they do not have to be deep in order that they may be sharp, and thus the width of the strip may be reduced a minimum amount in forming the notches, and the strip has a very large proportion of its original strength.

The length of material used for making fasteners is less with my corrugated fastener than with one made up entirely of curves, and the length of the cutting edge is correspondingly reduced.

When the V-shaped corrugations are used in combination with the form of cutting edge which I have illustrated, a very marked advantage is obtained, both as to the amount of power required to drive the fastener and the cleanness with which it enters the wood, and for these reasons they are more easily driven straight.

On account of the corrugations being sharp bends, they leave the wood between them in stronger shape than the curved fas teners, the wood being solid clear up into the bends instead of being crushed away from thebends as frequently happens with. fasteners having rounded bends. This means that the wood is in better condition to hold the fasteners so that a joint of greater strength is obtained.

The rolls used to form the V-shapcd corrugations wear much longer than those used to form rounded corrugations, since the rolls for forming rounded corrugations tend to assume the shape used for the V-shape corrugations.

The making of rolls for forming the V- shape corrugations is cheaper than the making of rolls for forming the rounded corrugations, since the latter require specially shaped cutters which mustbe accurately ground, while the former are made by ordinary angle cutters, which are easily ground.

()n account of my corrugations being V- shape instead of rounded, they nest together more perfectly when a strip is wound into a coil, so that a greater length of strip can be wound in a coil of a given size, thus ailowing a fastener driving machine to be run considerably longer without stopping to replenish the coils.

No portion of the cutting edge of my fastener extends directly across the grain of the wood at any point When the fastener is driven to unite two boards placed side by side. Since the curved corrugations tend to mash down the grain of the wood because they lie across the grain, they tend to cause the fasteners to tip both crosswise and lengthwise of the grain, and thus frequently result in failing to drive the fasteners in the position in which they were intended. As the cutting edge of my fastener, however, at no point lies across the grain, this difficulty is avoided.

-While I before described certain specific steps for the purpose of disclosing my in vention, such steps are to be considered merely as illustrative, and changes may be made therein without departing from the scope of the invention as defined in the appended claims.

I claim:

1. The method of making corrugated fasteners which comprises beveling one side edge of a sheet metal strip, corrugating such strip, and cutting oif the corners of the apexes of the corrugations on the edge which was previously beveled.

2. The method of making corrugated fasteners which comprises beveling one side edge of a sheet metal strip, corrugating such strip, and cutting notches at the apexes of the corrugations on the edge of the strip which was previously beveled, the notches being cut to such depth as not to extend inwardly substantially beyond the bevel previously provided.

3. The method of making corrugated fasteners which comprises beveling one side edge of asheet metal strip, corrugating such strip, and cutting notches at the apexes of the corrugations on the edge of the strip which was previously beveled, the notches being cut to such depth as to leave cutting edges formed by the original bevel, respectively between adjacent notches.

4. The method of making corrugated fasteners which comprises beveling one side edge of a sheet metal strip, corrugating such strip, and cutting notches at the apexes of the corrugations on the edge of the strip which was previously beveled, the notches being cut to such depth as not to extend inwardly substantially beyond the bevel previously provided, and to leave cutting edges formed by the original bevel, respectively between adjacent notches.

5. The method of making corrugated fasteners which comprises forming a double bevel on one side edge of a sheet metal strip, corrugating such strip, and cutting off the corners of the apexes of the corrugations on the edge which was previously beveled.

6. The method of making corrugated fasteners which comprises forming a double bevel on one side edge of a sheet metal strip, corrugating such strip, and cutting notches at the apexes of the corrugations on the edge of the strip which was previously beveled, the notches being cut to such depth as not to extend inwardly substantially beyond the bevel previously provided.

7. The method of making corrugated fasteners which comprises forming a double bevel on one side edge of a sheet metal strip, corrugating such strip, and cutting notches at the apexes of the corrugations on the edge of the strip which was previously beveled, the notches being cut to such depth as to leave cutting edges formed by the origi nal bevel, respectively between adjacent notches.

8. The method of making corrugated fasteners which comprises forming a double bevel on one side edge of a sheet metal strip, corrugating such strip, and cutting notches at the apexes of the corrugations on the edge of the strip which was previously beveled, the notches being cut to such depth as not to extend inwardly substantially be yond the bevel previously provided, and to leave cutting edges formed by the original bevel, respectively between adjacent notches.

In testimony that I claim the foregoing I have hereunto set my hand.

FRANK P. PRINDLE.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, D. 0. 

